Those skilled in the art know that sensors are utilized on vehicles for determining vehicle operating characteristics, for example, vehicle wheel speed and vibration. Also, it is known that sensors may be characterized as active and passive, which require different controller hardware.
Active sensors often include electronic circuitry that requires external power to function. For example, an active speed sensor may utilize a “Hall Effect” element that senses the poles on a multi-pole magnet. As another example, a vibration/acceleration sensor generates signals that may originate from an accelerometer. Typically, the “Hall Effect” element and the accelerometer require power which originates from an external source. On the other hand, a passive sensor provides its own power. For example, a passive variable reluctance (VR) sensor, utilized as a speed sensor, may comprise a coil of wire wound around a pole piece of a magnet. When sensing a suitable exciter ring (a.k.a., “tone wheel”), this passive speed sensor provides the controller an approximately sinusoidal signal with a frequency that is proportional to the vehicle wheel speed. Thus, it is typical that hardware that is utilized to connect active sensors with a controller may not work to connect passive sensors with the controller. Also, different hardware is utilized to connect vibration/accelerometer signals with the controller that may not work to connect other active sensors and/or passive sensors with the controller.
Examples of relevant art, where vehicle wheel sensors are utilized in a vehicle, are as follows. U.S. Pat. No. 4,660,146 to Kubo discloses an anti-lock brake control system having wheel sensors at each wheel. Each wheel sensor is connected to a controller so that the controller can determine instantaneous wheel speed and instantaneous wheel acceleration, or deceleration, for each wheel.
U.S. Pat. No. 5,184,069 to Adler et al. teaches a wheel speed sensor system that generally discloses an active sensor or a passive sensor being connected to a system controller.
U.S. Pat. No. 5,576,960 to Maeda generally discloses a front wheel sensor and a rear wheel sensor of a motorcycle connected to an interface circuit and an anti-lock brake system (ABS) controlling unit.
U.S. Pat. No. 6,442,502 to Lohberg et al. provides a system for sensing the rotational speed of an incremental pulse generator by means of a sensor module. The sensor module is coupled magnetically to the encoder by way of an air gap. The sensor module is connected to an electronic control unit by way of a two-wire line. The two-wire line is used for the energy supply and the signal exchange. The electronic control unit may send control signals to the sensor module via the two-wire line. The control signals relate to the internal operations of the sensor module.
U.S. Pat. No. 6,339,322 to Loreck et al. teaches a sensor connected to an electronic control unit. The sensor itself has a controllable power source, which delivers a load-dependent current. Apparently, the sensed rotational speed of a wheel can be transmitted from the sensor to the electronic control unit (ECU) via two lines. A change between two predetermined current amplitudes transmits the sensor signal across one of the lines to the ECU. The frequency or duration of the change in current amplitude contains the data about the rotational speed being measured.
U.S. Pat. No. 6,133,728 to Manlove et al. provides for a variable reluctance magnetic pick-up sensor connected to a pick up coil via two lines. A differential voltage is produced in the lines by the sensor in response to rotation of a wheel.
Thus, active and passive vehicle wheel sensors, including those briefly described above, would benefit from an apparatus and a method that could directly connect both types of vehicle wheel sensors, while providing the necessary connectivity, power, and communication between the sensors and the controller through efficient and cost effective means.